Fluid mover



E. C. OKRESS Aug. 13, 1968 FLUID MOVER 2 Sheets-Sheet 1 Filed 001:. 10, 1966 PERIODIC ELECTRIC POTENTIAL SOURCE INVENTOR. ERNEST C. OKRESS AT TO RNEY E. C. OKRESS Aug. 13, 1968 FLUID MOVER 2 Sheets-Sheet 2 Filed Oct. 10, 1966 FIG. 3A

INVENTOR ERNEST C. OKRESS BY 8 I am 7 9-,

ATTORNEY GAS FLOW/T United States Patent 3,396,662 FLUID MOVER Ernest C. Okress, Elizabeth, N.J., assignor to American Standard Inc., a corporation of Delaware Filed Oct. 10, 1966, Ser. No. 585,667 Claims. (1. 103--1) ABSTRACT OF THE DISCLOSURE This invention relates to a fluid mover which includes a main tube through which a fluid, such as air, is to be moved, and two other tubes both of which may be coaxial with the main tube. Between the two inner tubes there is positioned an ionizer having one or more charge emitters and one or more charge collectors, the emitters and collectors being spaced axially from each other. A dielectric constrictor is interposed between an emitter and a collector and it is provided with an orifice to permit molecules of the fluid, such as air, to be dragged from the emitter to the collector and to be subject to a Venturi-like effect.

This invention pertains to dielectric fluid movers and more particularly to methods and means for electrically imparting common directed momentum to a dielectric field.

Conventional dielectric fluid movers require mechanical moving parts which are generally indirectly driven by electrical means such as motors. Such devices have characteristic disadvantages. There have been proposals to provide devices for moving dielectric fluids such as air which directly utilize electricity. However, such state of art devices for air are impractical due to inadequate efliciency pressure gradient and mass flow rate. This is due essentially to the inadequate electric field gradient by virtue of electric breakdown and more importantly due to inadequate free unipolar ion density from corona ionizers. Furthermore, the latter generate more toxic compounds (i.e., ozone, nitrogen oxides, etc.) than unipolar ions. In order to do direct electrical Work on the air molecules they must first be ionized. The ions are accelerated by electric or crossed electric and magnetic fields in a direction of the electric field or in a direction normal to the crossed electric-magnetic field. The collision of the unipolar ions with air molecules causes the air molecules to move forward of the ions and an air flow is generated. However, normally, any ionizing agency applied to air under conditions in which it is ionized, excited molecules are also formed, which dissociate into radicals, such as oxygen and nitrogen atoms producing toxic impurities. In particular, ozone and oxides of nitrogen are formed. Such by-products, even in small quantities, can cause physiological damage. It has been found that effective ionizers such as corona discharge means create ozone in quantities significantly greater than safe industrial minimums.

In my co-pending application Ser. No. 379,183, filed June 30, 1964, for an Air Blower, I disclosed improved means for electrically moving air. These means utilized the fact that periodic electric field directed unipolar ions, derived from suppressed or arrested discharge, hereinafter called suppressed discharge, of a partially ionized dielectric fluid medium produce an aerostatic or aerodynamic pressure gradient in the dielectric fluid along the 'ice electric accelerating field axis through directed collision of ions with molecules of the medium and so transfer directed momentum from the ions to the molecules of the dielectric fluid. The resulting static or dynamic pressure gradient causes the medium to be moved along the electric field axis between the charge emitter toward the accelerating electrode or charge collector thus creating an electric air stream or electric wind. This ion drag or pressure gradient is proportional to the dielectric constant of the medium, and to the square of the maximum electric field between the charge emitter and charge collector electrode.

Since the pressure is proportional to the square of the electric field, presumably high pressures can be attained with high electric fields. However, if a constant (i.e., direct current, D.C.) electric field is employed low impedance electric breakdown of the medium between the electrodes occurs at a critical value of the electric field or voltage, beyond which electric energy cannot be effectively coupled into the medium to do the desired work, For air at atmospheric conditions, between the order of 21 mil radius of curvature electrode serving as charge emitter and adjacently disposed larger radius of curvature or planar apertured electrode serving as charge collector, the low impedance electric breakdown voltage amounts to about 30 kv./cm., with allowance for the fact that just below the characteristic voltage stable operation may be realized before the streamer crosses the gap between electrodes preventing further input electrical energy into desired work.

In order to overcome this limitation of electrical energy input into the medium to gain useful work, the apparatus of my co-pending application employed an array of asymmetric (charge emitter and charge collector) electrodes. These electrodes are appropriately disposed and energized by unipolar voltage pulses of such short duration (in the order of nanoseconds) to cause or not to cause ionization of the medium as desired, between said electrodes, but not to cause low impedance electric breakdown (i.e., streamer between electrodes) of the medium, such as air, between the electrodes regardless of the amplitude of the applied pulse voltage. Therefore, this discharge may be referred to as suppressed or arrested. In fact for maximum coupling of electrical energy into the dielectric medium, the maximum voltage and minimum pulse duration is indicated. For maximum power into the dielectric medium the maximum voltage and minimum pulse duration applied at maximum repetition rate is indicated, consistent with low impedance electric breakdown limitations.

The constant and periodic pulsed electric wind or aerodynamic pressure or propulsion force, resulting from each electrode-pair arises from a not fully known mechanism. However, to the extent that the mechanism is known the following theory applies. Since only electric charges can interact directly with the electric field between the electrodes in response to the applied voltage pulses, a means must exist for the transfer of kinetic energy from charges to the neutral gas particles. Otherwise, the directed momentum transfer and energy conversion efliciency is correspondingly low since most of the kinetic energy of the gas stream is carried by the electric charges. Furthermore, energy transfer can only occur by virtue of electric attractive forces and collisions between particles. The charges, ions and electrons, in absorbing their energy from an external electric source via the electrodes, are accelerated. To realize high efliciency of aerodynamic pressure generation, the gas or air stream of essentially neutral atoms and molecules must be accelerated. Now, due to the relative mass of the electron and ion or neutral molecules, the former imparts negligible energy to the latter on impact, while the ion, of comparable mass with the neutral molecules imparts at least half or most of its kinetic energy to the molecule on impact, depending upon whether the impact is radial or tangential on the average. Hence, ions are capable of gaining correspondingly less velocity Compared with the electrons under the influence of the same electric field. So While electrons can excite and ionize atoms, ions correspondingly do not. Hence, since the electrons respond spontaneously to the applied electric field, their action on the positive ions via coulomb attraction drags the positive ions behind them. The latter in colliding with the neutral gas molecules push them forward of themselves. This follows from the fact that at a given voltage, the electron velocity is already a couple orders greater than that of the ion even at the order of unity voltage. However, this is not to imply that unipolar ions cannot be sufliciently accelerated by sufi'iciently high applied unipolar electric field or alternating polarity electric field, provided, in the latter case, that the transit time between the electrodes is much less than a voltage pulse duration. While, in the immediate vicinity (i.e. -0.l mm.) of the small radius of curvature charge emitter, bipolar charge region prevails, further out the unipolar charge region prevails up to the charge collector.

In any event, the net effect of colliding ions with the fluid molecules is to push them ahead of the ions along the axis of the applied electric field. While the ions terminate on the charge collector, the fluid molecules with imparted momentum from the ions are virtually unaffected by the electric field. The effect is an electric wind at the expense of absorption of the applied electric energy across the electrodes.

This foregoing mechanism may be compared with that of a solid in which the energy transfer occurs via the positive ions in the crystal lattice. The conduction electrons, contributed by the atoms of the solid, flowing (or induced by virtue of motion in a magnetic field) in response to the applied electric gradient, experience a retarding force communicated to the positive ions due to coulomb attractive forces. However, in this case the positive ions are relatively fixed in the crystal lattice and hence the whole conductor alters kinetic energy. Such a process arises from the fact that the atoms, which contribute the conduction electrons, are closely packed in a solid so that interparticle electric forces are great.

While it is true that a small radius of curvature charge emitter (such as a point or fine wire) and a charge collector (such as an apertured plate) corona or ionizer can produce high concentration of free small ions, ion generation is generally inefficient due to the fact that the same electric field which creates the ions also collects them. This effect may be mitigated to a degree by partially shielding the charge collector with a dielectric sleeve. Furthermore, since D'.C. corona ionizers operate at a mean voltage gradient of about 1000 V/cm., the average velocity of the ion is a substantial fraction of sound velocity in that medium. Hence, at the usual air flow (i.e., about ft./sec.) through the corona ionizer, only a small fraction of the total ion current is extracted for useful work on the air molecules.

In summary, the cardinal limitations of the state of art corona means include:

(1) Limited input energy or power into the dielectric field for useful work (e.g., one watt/cm.

(2) Electric breakdown in air at atmospheric conditions cause a low impedance streamer bridge across the electrodes (e.g., kv./cm. or for point or fine wire to plane corona discharge about 15 kv.).

(3) Due to necessary close spacing of charge emitter i and charge collector, aerodynamic friction drop dissipates the major share of the generated aerodynamic pressure.

(4) Due to the necessary low voltage of operation, limited by electric breakdown, the high ion mobilities of the gaseous medium result in very low efiiciency and emodynamic pressure (e.g., 1% and 1 mm. H O, respectively).

It is accordingly a general object of the invention to provide an improved dielectric fluid mover.

It is another object of the invention to provide an improved method of moving a dielectric fluid.

It is a further object of the invention to provide an improved air blower or fan or the like, which require no mechanical moving parts.

It is yet a still further object of the invention to provide an air blower or fan, which exhausts a minimum amount of toxic atmospheric compounds.

It is still another object of the invention to provide an air blower or fan which operates directly from commercial and domestic power lines and utilizes a minimum of electrical power.

It is also an object of the invention to provide an air blower or fan, capable of efficient generation of aerodynamic pressure and air velocity and which is easily portable and simple in construction.

It is more specific object of the invention to provide an improved air blower or fan of the type utilizing a pulsed unipolar or alternating polarity electric field which much more efliciently generates aerodynamic pressures than the state of art direct electric air blowers.

Briefly, the apparatus of the invention contemplates at least a charge emitter electrode and a charge collector electrode spaced therefrom in a region containing ionizable gas molecules. A dielectric constrictor is disposed between the electrodes. The constrictor is provided with an orifice through which molecules may pass. The electrodes are connected to a periodically pulsed voltage source having a pulse duration insufiicient to cause low impedance electric breakdown between the electrodes, but having an amplitude and repetition rate suflicient for the desired energy or power to be coupled into the dielectric fluid, to accelerate without gas ionization or to cause volume ionization of some of the gas molecules. The ionized molecules are separated into a unipolar ion stream and accelerated in a preferred direction so as to collide with neutral gas molecules in order to establish an aerodynamic pressure gradient or volumetric flow of the dielectric fluid through the charge collector aperture.

The invention provides the following advantages:

(1) Much higher input energy (i.e., joules/pulse) and power (i.e., kilowatts) into the medium for useful work by virtue of the pulse duration being so brie-f i.e., nanoseconds) and repetition rate not too high (i.e., l0 kilo pulses/second) as to not initiate low impedance electrical breakdown between electrodes.

(2) Periodic pulse corona operates stably at much higher unipolar ion density and current than possible with state of art corona (e.g., to and beyond hectoamperes as compared with state of arts coronas deciamperes).

(3) Due to suppressed or arrested high voltage operation unipolar ions can be more effectively extracted from the suppressed or arrested discharge and enhanced clustering causes ion mobility to be reduced (e.g., 10* to 10 meter /volt, second) so that these factors further increase efiiciency (e.g., 30 to of aerodynamic pressure generation than possible by state of art corona means (e.g., 1%).

(4) Due to high impedance electrical operating parameters, much larger electrode spacings and hence much lower aerodynamic or aerostatic friction loss per stage is realizable than by state of art corona means.

(5) Much higher fluid dynamic pressure (e.g., in air at N.T.P. the order of from l0 to or even 1000' mm. H O or more per stage) is possible.

Other objects, features and advantages of the invention will in part be obvious and will in part appear hereinafter.

The invention, accordingly, comprises the features and arrangements which are exemplified with respect to a particular combination of elements while the scope of the invention will be indicated in the claims.

For a further understanding of the nature and objects and advantages of the invention, reference should be made to the following detailed description read in connection with the accompanying drawings, in which:

FIG. 1 is an axial section, partialy in schematic form of a single stage of the dielectric fluid mover employing an interactor in the form of a dielectric constricted ionizer and unipolar ion accelerator, in accordance with the invention.

FIG. 2. is a quadrant view of the interactor of FIG. 1 employing electrodes in accordance with the invention.

FIG. 3 is an enlarged cross-sectional view of the electrode configuration of the interactor of FIG. 2.

FIG. 3A is an enlarged sectional view of the tip of the charge emitter electrode of FIG. 3.

FIG. 4 is an enlarged sectional view of an alternate embodiment of the electrode configuration.

Referring now to FIG. 1, a dielectric fluid mover is shown comprising a hollow tubular conduit 12 having disposed therein a dielectric constricted ionizer hereinafter referred to as interactor 14, that is energized by periodic electric potential source 16. When the fluid mover 10 is placed in air and periodic electric potential source 16 is operating, a periodic unipolar (or alternating polarity subject to conditions previously referred to) electric field is established in the region of tubular conduit 12 occupied by interactor 14. Ionization of the air molecules in the region of interactor 14 takes place as described previously and an aerostatic pressure gradient or fluid fiow is established in this region. Accordingly, air is drawn into the inlet 18 and expelled from the outlet 20 of dielectric fluid mover 10.

In order to enhance the operating efiiciency of aerodynamic pressure generation, a particular configuration of the interactor 14 is utilized. Essentially, the interactor requires a charge emitter electrode and a charge collector electrode axially spaced from each other. Interposed between the electrodes is a dielectric constrictor provided with an orifice so that the air molecules dragged from the emitter to the collector are subject to a Venturi-like eifect without seriously constricting the discharge and flow. Basically, then more efficient aerodynamic pressure generation is obtained by periodically subjecting the air in the interaction region to a pulsed unidirectional (or alternating polarity subject to cited conditions) electric field so as to cause a suppressed or arrested discharge and resulting unipolar ions to be extracted therefrom, and aerodynamically guiding the air molecules from the charge emitter electrode to the charge collector electrode.

Interactor 14, a quadrant portion of which is shown in FIG. 2, comprises a central hollow tube 22 and an outer tube 23 of common dielectric material. Radiating from tube 22 to tube 23 are a plurality of vane-like support spokes 24 of dielectric material. The top edge of spokes 24 are provided with an electrical conductor 26. Extending downward and supported by spokes are a plurality of concentric charge collector electrodes 28 which are radially spaced from each other. There is an electrical connection between electrodes 28 and the electrical conductor 26 on the top edges of spokes 24. Afiixed to and extending downward from electrodes 28 are a plurality of concentric and radially spaced ventura 30 of a dielectric material. A second plurality of dielectric support spokes 32 extend along radii between tubes 22 and 23. The bottom edge (as viewed in FIG. 2) of spokes 32 are provided with electrical conductors 34. Supported by spokes 32 are a plurality of concentric and radially spaced charge emitter electrodes 36. At least the top edges 38 of electrodes 36 are of electrically conductive material and are connected to the conductors 34 of the spokes 32.

Thus, all the charge collector electrodes 28 are connected to radial conductors 26; and all the charge emitter electrodes 36 are connected to radial conductors 34. Conductors 26 may be connected to the positive output terminal of source 16 if unipolar and conductors 34 are then connected to the negative output terminal of source 16 as shown schematically in FIG. 1. Accordingly, each time unipola'rity source 16 transmits a pulse, an electric field is established from charge emitter electrodes 36 to charge collector electrodes 28.

In FIG. 3, there is an enlarged cross-sectional view of the electrode-ventura-like configuration. Referring to the figure, there is shown the charge emitter electrode 36 comprising a stem 37 of dielectric material, having a triangular cross-section. A tapered tip emitter 38 of electrically conductive material longitudinally extends from the stem 37. As is shown in FIG. 3A, tip 38 terminates in an edge having the order of a mil radius of curvature. The dielectric ventura are both axially and transversely displaced from charge emitter electrode 36. The cross-section of each ventura 30 is a rectangle which is canted with respect to the axis of the emitter electrode 36. Thus, a constricted orifice or passageway 40 is provided from the emitter electrode 36 to the collector electrodes without significantly interfering with the periodic pulsed corona discharge. For operation, the transverse separation of the charge collector electrodes 28 may be of the order of centimeters. The axial separation from the base of the collector electrodes 28 to tip 38 may also be of the order of centimeters. The separation at the minimum clearances of the passageway 44} may be of the order of a centimeter. The axial distance from the minimum clearance region of passageway 40 to tip 38 may be of the order of a centimeter, and the minimum distance between tip 38 and ventura 36' may be of the order of a centimeter.

While the electrode geometry of FIG. 3 is operable, noise and aerostatic or aerodynamic pressure drop may be reduced by the configuration shown in FIG. 4 which employs similar elements which more effectively exploits aerodynamic properties. Since the configuration of FIG. 4 uses elements similar to those of FIG. 3 primed reference characters wlil be employed for like elements. In particular, emitter electrode 36 utilizes a stem 37 whose crosssection has carnbered side. The tip 38 is fixed to the base of stem 37 and has sides which concavely taper to a point.

Each of the ventura 30' has a cross section which concavely increases from point 46. In the region of passageway 4d, the profile changes to a concave geometry. Fixed to the back portion of each ventura 30 is a col lector electrode 28' which concavely tapers to a point.

It should be noted that the tip 38' extends into the region between the ventura 39'. The following dimensions are utilizable. The width of the stem 37' may be a small fraction of a centimeter. The minimum spacing between the ventura i.e., the gap at the narrowest point may be the order of a centimeter. The axial distance between the bottom of a collector electrode 28' and tip 38' may be the order of a centimeter. The axial distance from the gap at the narrowest point and the tip 38' may be the order of a centimeter.

For either embodiment the use of ventura enhances operation because it increases aerodynamic pressure without significantly interfering with the natural unipolar ion constriction and afiords means for measurement with minimum interaction and feedback.

A suitable periodic electric potential source 16 may generate unipolar (or alternating polarity under the conditions previously stated) voltage pulses having an amplitude of from 25 to kilovolts or more at a frequency of the order of 1,000 to 10,000 or more pulses per second. The pulse duration should be of from about 10 to about 1 nanosecond. Such pulse generators may take the form of the type described in the article entitled Subnanosecond Risetime Multikilovolt Pulse Generator by Daniel F. McDonald, et al., in vol. 36, No. 4 (April 1965) p. 504 of the Review of Scientific Instruments.

It should be noted that the surfaces of all the dielectric elements may be preferably made of or coated with a non-charging material such as Teflon to reduce space charge accumulation and thus avoid premature electric breakdown due to the unsymmetrical electrodes. To reduce charge accumulation in the space in the vicinity of the collector and hence avoid electric breakdown between the charge cloud and the structure it may be desirable to resort to alternating polarity app-lied electric voltage, under the conditions previously stated hereinbefore.

In addition, it should be realized that although only a single interactor having a single set of emitters and collectors has been shown it is understood that the inventive concept can be expanded to include the parallel or series operation of several charge emitter-collector units for greater aerostatic or aerodynamic pressure and mass flow rate of fluid. Similarly, compound (i.e., series/ parallel) operation analogous to a turbine is contemplated.

Furthermore, it should also be realized that periodic alternating polarity voltages and/or currents may be utilized for exciting the electrodes since with alternating polarity electric fields a reduction of downstream space charge accumulation may be desirable so as to avoid possible premature electric breakdown of the air.

There has thus been shown an improved method of moving a dielectric fluid by ionizing the dielectric fluid by means of a suppressed or arrested discharge in an interaction region by subjecting the dielectric fluid to a unipolar or alternating polarity periodic electric field of such brief pulse duration so as not to cause low impedance electric breakdown of the fluid between the electrodes across which the periodic electric field is impressed, and thus moving the fluid through the region.

Furthermore, there has been shown specific electrode configurations for enhancing the fluid dynamic pressure and eificiency.

It should be noted that while in the description of the invention, the specific fluid referred to was air, other dielectric fluids, such as aerosols, colloids, and dielectric liquids come within the scope of the invention.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efliciently attained and, since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

What is claimed is:

1. In combination, at least one charge emitter electrode, at least one charge collector electrode axially spaced from said emitter electrode, a constrictor of dielectric material interposed between said electrodes, said collector and constrictor being provided with an orifice to permit dielectric fluid communication from the suppressed discharge region about said charge emitter electrode to the unipolar ion acceleration region about said charge collector electrode, and means for applying characteristic periodic voltage pulses to said electrodes.

2. In combination, at least one charge emitter electrode, at least one charge collector electrode axially spaced from said emitter electrode, a constrictor of dielectric material interposed between said electrodes, said collector and constrictor being provided with an orifice to permit dielectric fluid communication from the suppressed discharge region about said charge emitter electrode to the unipolar ion acceleration region about said charge collector electrode, and means for applying characteristic periodic voltage pulses to said electrodes, the pulse duration and repetition rate being such as to prevent low impedance electric breakdown, due to streamer bridging the gap between said electrodes.

3. In combination, at least one charge emitter electrode, at least one charge collector electrode axially spaced from said emitter electrode, venturi means of dielectric material interposed between said electrodes to provide guided fluid communication from the suppressed discharge region about said charge emitter electrode to the unipolar ion acceleration region about said charge collector electrode without interfering with electrical discharge nor inducing undue aerodynamic friction loss between said electrodes, and means for applying characteristic periodic voltage pulses to said electrodes, the pulse duration and repetition rate being such as to prevent low impedance electric breakdown, due to streamer bridging the gap between said electrodes.

4. Apparatus for generating an electric wind comprising: at least one charge emitter electrode, said emitter electrode comprising a stem of dielectric material and a tapered tip charge emitter of electrically conductive material extending longitudinally from said stem; at least a pair of charge collector electrodes, each of said collector electrodes being obliquely displaced from said emitter electrode and symmetrically disposed with respect to the crosssectional axis of said emitter electrode, said collector electrodes each comprising a support of dielectric material and a plate-like collector of electrically conductive material disposed on said support in a region remote from said tapered tip emitter, each of said supports having a cross-section to define a constricted passageway from said tapered tip emitter to said plate-like collector; and means for applying periodic voltage pulses to said tapered tip emitter.

5. The apparatus of claim 4 wherein said stern has a substantially triangular cross-section.

6. The apparatus of claim 4 wherein said stem has a double camber cross-section.

7 The apparatus of claim 4 wherein said tapered tip emitter terminates in a region having a radius of curvature of substantially the order of a mil.

8. The apparatus of claim 4 wherein said supports have a rectangular cross-section.

9. The apparatus of claim 4 wherein said supports have a cross-section which concavely increases from a point adacent said tapered tip emitter and gradually changes to a concave region.

10. The apparatus of claim 4 wherein said charge collector electrodes have a cross-section which concavely tapers to a point.

11. The apparatus of claim 4- wherein the cross-section of said tapered tip emitter concavely tapers to a point.

12. The apparatus of claim 4 wherein said tapered tip emitter extends into the region between said supports.

13. A direct electric blower comprising: a plurality of concentric charge emitter electrodes radially spaced from each other, each of said charge emitter electrodes being an annulus and including a portion of electrically conductive material, a plurality of concentric charge collector electrodes radially spaced from each other and axially displaced from said charge emitter electrodes, each of said charge collector electrodes being radially oflfset from one of said charge emitter electrodes; a plurality of concentric dielectric constrictor means axially interposed between said charge emitter and said charge collector electrodes for providing constricted passageways from said charge emitter electrodes to said charge collector electrodes; and means for applying pulses of electrical energy to said electrodes.

14. A direct electrical method of directionally accelerating molecules of a dielectric fluid which consists in periodically subjecting the fluid in a particular region to a pulsed electric field for ionizing portions of the dielectric fluid in said region, preventing low impedance electric breakdown of said fluid by maintaining very short pulses and fluid dynamically guiding the fluid through said particular region.

15. A method of axially accelerating molecules of air by means of unipolar ions electrically extracted from suppressed electric discharge in a tubular chamber which consists in periodically establishing a pulsed electric field between two axially displaced regions of said chamber, preventing low impedance electric breakdown of the fluid between said two regions and aerodynamically guiding the flow of the air molecules from the first region to the second region.

References Cited UNITED STATES PATENTS 2,279,586 4/ 1942 Bennett 230--69 3,054,553 9/1962 White 1031 3,212,442 10/1965 Jorgenson 103-1 3,267,859 8/1966 Jutila 1031 10 ROBERT M. WALKER, Primary Examiner. 

